Use of hemispherical photography for plant area index determination in young olive trees (Olea europaea L.)

M. P. Simões^1,2, C. Pinto-Cruz^1,2, A.F. Belo¹, L.F. Ferreira¹, J.P. Neves¹ & M.C. Castro^2,3

RESUMO

O índice de área foliar (LAI) é um parâmetro essencial para a caracterização da estrutura das copas e consequentemente para a avaliação da vitalidade das plantas.

Neste estudo compararam-se valores de LAI obtidos através de métodos directos destrutivos e através da análise de fotografia hemisférica, em oliveiras jovens das cultivares ‘Galega’ e ‘Cordovil de Serpa’, num olival da região de Moura.

Os valores determinados por fotografia hemisférica subestimaram significativamente (P<0,05) os obtidos pelas medições directas.

Assumindo que os métodos directos estimam o LAI com maior precisão, os valores obtidos destrutivamente foram utilizados como referência para o cálculo de equações de regressão entre os resultados dos métodos indirecto e directo. A partir destas ajustaram-se os valores determinados através da fotografia hemisférica, de forma a permitir a sua aplicação futura para avaliação do LAI em oliveiras jovens.

ABSTRACT

The determination of leaf area index (LAI) is essential in the characterization of the canopy structure and plants vitality evaluation.

In this study destructive measurements of LAI were compared with values obtained by hemispherical photography analysis, of young olive trees cv. Galega and cv. Cordovil de Serpa, in an olive orchard of Moura region.

As the direct method is assumed to be the most correct for estimating LAI, this method served as reference for the performance of the indirect methods. In order to be able to use the indirect methods to determine the LAI in the future, regression equations have been calculated taking into consideration the results of the indirect and the direct methods.

Our results suggest that this procedure is an alternative method suitable to LAI determination in young olive trees after specific calibration.

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REFERÊNCIAS BIBLIOGRÁFICAS

Alexandre, A. & Afonso, T. 2005. Cartografia de solos à escala da exploração: aplicação a um ensaio de olival. Jornadas Científicas do ICAM, 15-16 de Dezembro, Universidade de Évora, Évora.        [ Links ]

Barnett, V. & Lewis, T. 1994. Outliers in Statistical Data. 3 ^rd ed. John Wiley & Sons, England. 584 p.

Campbell, G.S. & Norman, J.M. 1989. The description and measurement of plant canopy structure. In G. Russell, B. Marshall & P.G. Jarvis (eds) Plant Canopies: Their Growth, Form, and Function, pp. 1-19. Society for Experimental Biology: 31. Cambridge Univ. Press, Cambridge.

Chen, J.M. 1996. Optically-based methods for measuring seasonal variation of leaf area index in boreal conifer stands. Agric. For. Meteorol., 80: 135-163.

Cohen, S., Striem, M.J., Bruner, M. & Klein, I. 2000. Grapevine leaf area index evaluation by gap fraction inversion. Acta Hort., 537: 87-93.

Englund, S.R., O’Brien, J.J. & Clark, D.B. 2000. Evaluation of digital and film hemispherical photography and spherical densiometry for measuring forest light environment. Can. J. For. Res., 30: 1999-2005.

Gazarini, L.C., Araújo, M.C.C., Borralho, N. & Pereira, J.S. 1990. Plant area index in Eucalyptus globulus plantations determined indirectly by a light interception method. Tree Physiology, 7: 107-113.

Gucci, R., Cantini, C., van Gardingen, P. & Sharp, L. 1999. Determination of plant area index of olive trees by hemispherical photography.

Jonckheere, I., Fleck, S., Nackaerts, K., Muys, B., Coppin, P., Weiss, M. & Baret, F. 2004. Review of methods for in situ leaf area index determination Part I. Theories, sensors and hemispherical photography. Agric. For. Meteorol., 121: 19-35.

Mariscal, M.J., Orgaz, F. & Villalobos, F.J. 2000. Modelling and measurement of radiation interception by olive canopies. Agric. For. Meteorol., 100: 183-197.

Martens, S.N., Ustin, S.L. & Rousseau, R.A. 1993. Estimation of tree canopy leaf area index by gap fraction analysis. For. Ecol. Manag., 61: 91-108.

Mussche, S., Samson, R., Nachtergale, L., De Schrijver, A., Lemeur, R. & Lust, N. 2001. A comparison of optical and direct methods for monitoring the seasonal dynamics of leaf area index in deciduous forests. Silva Fennica, 35: 373-384.

Nilson, T. 1999. Inversion of gap frequency data in forest stands. Agric. For. Meteorol., 98-99: 437-448.

Nilson, T. & Kuusk, A. 2004. Improved algorithm for estimating canopy indices from gap fraction data in forest canopies. Agric. For. Meteorol., 124: 157-169.

Norman, J.M. & Campbell, G.S. 1989. Canopy structure. In R.W. Pearcy, J. Ehleringer, H.A. Mooney & P.W. Rundel (eds) Plant Physiological Ecology: Field Methods and Instrumentation, pp. 301-325. Chapman and Hall, New York.

Rapoport, H.F. 2001. Botanica y morfologia. In D.Barranco, D. Fernández Escobar & L. Rallo (eds) El Cultivo del Olivo, pp. 215-254. Ed. Mundi-Prensa. 4ª ed., Madrid.

Roxburgh, J.R. & Kelly, D. 1995. Uses and limitations of hemispherical photography for estimating forest light environments. New Zealand Journal of Ecology, 19: 213-217.

Villalobos, F.J., Orgaz, F. & Mateos, L. 1995. Non destructive measurement of leaf area in olive (Olea europaea L.) trees using a gap inversion method. Agric. For. Meteorol., 73: 29-42.

White, M.A., Asner, G.P., Ramakrishna, R.N., Privett, J.L. & Running, S.W. 2000. Measuring fractional cover and leaf area index in arid ecosystems: digital camera, radiation transmittance, and laser altimetry methods. Remote Sense. Environ., 74: 45-57.

Whitford, K.R., Colquhoun, I.J., Lang, A.R.G. & Harper, B.M. 1995. Measuring leaf area index in a sparse eucalypt forest: a comparison of estimates from direct measurement, hemispherical photography, sunlight transmittance and allometric regression. Agric. For. Meteorol., 74: 237-249.

¹ Dep. Biologia, Universidade de Évora, Apartado 94, 7002-554 Évora; e-mail: mps@uevora.pt; ²Instituto de Ciências Agrárias Mediterrânicas (ICAM), Universidade de Évora; ³Dep. Planeamento Biofísico e Paisagístico, Universidade de Évora.